Semi-solid rocket fuel with aluminum naphthenate containing about seven percent combined aluminum



SEMI-SOLID ROCKET FUEL WITH ALUMINUM NAPHTl-ENATE QIONT a l=- ABOUT SEVEN PERCENT COMBWED AL Charles R. Morton, ummit, N.J., and Gerald J. Horvitz, Woodmere, and Nicholas J. Nicholas, Greenlawn, N.Y., assignors to National Research 8; Development Corp, New York, N.Y., a corporation of Delaware No Drawing. Filed July 6, 1959, Ser. No. 824,539

9 Claims. (Cl. 149-48) This invention relates to semi-solid fuels and, more particularly, to such suitable for power generation including rocket propulsion.

An object of our invention is to produce a semirigid or plastic fuel suitable for propelling rockets and missiles, as well as power generation in boilers of conventional type with fuel combustion equipment designed to burn semi-solid fuelfor steam generation. It is also to produce such a fuel for use in direct combustion to generate power in turbo-machinery to produce electric or hydraulic power output or a combination of both. It may also be used to send the products of jet combustion directly into water to produce steam or other forms of thermal energy. The fuel itself includes oxidizable material such as finely-divided carbon, organic compounds or metal powders, strong oxidizing material and a plasticizer in the form of a gelled straight chain hydrocarbon liquid, an aromatic liquid or a combination of both. Specific examples of such oxidizable material other than carbon are organic or carbon compounds such as kerosene, aniline, unsymmetrical dimethylhydrazine and certain alcohols, While the metal powder group may include lithium and its hydride, boron and certain oxidizable compounds thereof, such as decaborane, as well as beryllium and certain oxidizable compounds thereof.

Another object of our invention is to improve over solid fuels suitable for rocket propulsion and combining similar oxidizable material and strong oxidizing agents, by providing for greater stability in a new propellant that is not affected by moderate changes in pressure, temperature or impact, thereby resulting in a mixture that gives optimum safety in handling and storage, such as is not the case with dry rigid propellant mixtures of equivalent propelling force.

. A further object of our invention is to provide a semisolid fuel suitable. for rocket propulsion employing a gelling agent used to partially solidify liquid hydrocarbons,

' which agent is preferably processed in the ,form of an aluminum naphthenate having a high percentage of aluminum and employing an oxidizing agent selected from the nitrates, chlorates, perchlorates, peroxides, and picrates of ammonia, alkali and other metals, nitrocellulose, nitroglycerine and others in the same category.

A still further object of our invention is the provision of a semi-solid fuel suitablefor rocket propulsion including a hydrocarbon gelled by aluminum naphthenate, an oxidizer and a suitable proportion of carbon in the form of lamp black, finely-divided calcined petroleum coke, ground charcoal or coal, which additional carbon sup-plements the carbon and hydrogen in the plasticizing hydrocarbon base by providing additional oxidizable material.

These and other objects and advantages will become apparent from the following detailed description; It will be understood that the description is for purpose of illustration and does not define the scope or limits of the in vention, reference being'had for the latter purpose to the appended claims.

We will now describe, in detail, desirable embodiments spasms Patented Feb. 27, 1962 tion, by Weight, of aluminum naphthenate having a high aluminum content. We have tested and found very'satisfactory in the tests below noted, an aluminum naphthenate having an aluminum content of around about 7 percent (7.55% was found to be a very practical percentage), with a liquid hydrocarbon fuel such as gasoline, with the following results in basic physical properties:

Aluminum Naphthenate With High Percent of Aluminum in Liquid Hydrocarbon Fuel (by Weight) No. 1 mixture, 2.6% A tacky viscous liquid.

No. 2 mixture, 3.8% A tacky but more viscous liquid.

No. 3 mixture, 7.3% A tacky gel.

No. 4 mixture, 10.6% A gel.

No. 5 mixture, 13.6% Do.

Serially using the mixtures above designated, we have prepared the following representative ammonia and alkaline earth containing products or compositions of matter:

25% of the No. 1 mixture plus of a mixture of 30% calcined petroleum coke and 70% ofammonium nitrate resulted in a tacky gelled mass.

Product No. 1.20% of the No. 1 mixture plus of the same mixture of 30% calcined petroleum coke and 70% ammonium nitrate gave a moldable mass.

On the other hand, when using only 5% of the No. 1 mixture and 95% of the same mixture of 30% calcined petroleum coke and 70% ammonium nitrate, a product resulted which was too powdery to be molded.

When the proportion of the No. 1 mixture was increased to 30% and mixed with 70% of a mixture of 30% graphite and 70% ammonium nitrate, a tacky gelled mass resulted. On the other hand, using the above mixture with a mere substitution of lamp black for the graphite, a powdery mass resulted. When the proportion of lamp black in the added mixture was reduced from 30% to 10% and the proportion of the ammonium nitrate increased from 70% to a satisfactory tacky gelled mass resulted.v

Continuing the tests and now using the No. 2 mixture and mixing 20% of that with 80% of a mixture of 30% graphite and 70% ammonium nitrate, a powdery mass resulted. However, upon increasing the proportion of the No. 2 mixture to 30% and mixing it with 70% of the same 30% graphite plus 70% ammonium nitrate mix ture, a satisfactory tacky gelled mass resulted.

Product No. 2.Upon testing the No. 3 mixture, we added to 25% thereof, 75% of 2. 5% lamp black plus ammonium nitrate mixture and obtained a moldable mass. On the other hand, when the same No. 3 mixture was reduced to 15% and added to 85% of the same 5% lamp black plugs 95% ammonium nitrate mixture, the product obtained was powdery. When the proportion No. 3 mixture was increased to 30%, and 70% of the same 5% lamp black plus 95 ammonium nitrate mixture was added, a satisfactory tacky gelled mass resulted.

Product No. 3.When 25% of the No. 3 mixture was combined with 75 of a 5% lamp black plus 95 ammonium perchlorate mixture, a mold'able mass resulted.

Product No. 4.-When half of the ammonium perchlorate in the above product was replaced by ammonium nitrate, a moldable mass resulted.

Product No. 5..When 33% of the same No. 3 mixture was added to 67% of a mixture of the same 5% lamp black and 95 magnesium perchlorate mixture, a moldable mass also resulted.

Product No. 6.Employing 25 of the No. 4 mixturewith 75 of a mixture of 5% lamp black and 95 ammonium nitrate, a moldable mass was obtained.

When the same proportion of ammonium perchlorate was substituted for the ammonium nitrate in the above mixture, the product was powdery. When the proportion of the No. 4 mixture was increased to 30%, and 70% of a mixture of 5% lamp black and 95% ammonium perchlorate was added, the product was powdery.

Product No. 7.When the proportion of No. 4 mixture was increased to 35%, and 65% of the same lamp black-ammonium perchlorate mixture was added, the product was moldable.

When 25% of the No. 4 mixture was added to 75% of a 5% lamp black-95 magnesium perchlorate mixture, a powdery mass resulted. When the proportion of No. 4 mixture was increased to 30% and the proportion of the lamp black-magnesium perchlorate mixture, above referred to, decreased to 70%, the product was still powdery.

Product No. 8.However, when the proportion of No. 4 mixture was increased to 35% and the proportion of the same lamp black-magnesium perchlorate mixture decreased to 65%, a moldable mass resulted.

The. burning qualities of some of the aforesaid products as identified by numbers, are as follows.

Product No. 1: Smooth burning, but calcined petroleum coke not completely oxidized.

Product Nos. 2 and 6: Smooth burning.

Product Nos. 3, 4, 5, 7 and 8: Smooth burning with propelling force.

As simulating a rocket for testing some of the above products, a length of copper tubing was sealed at one end. and the prepared semi-solid product inserted along with an igniter. The other end of said tubing was partially closed by squeezing to simulate an exhaust outlet. The propellant was fired by applying heat to the igniter. The following results were noted.

Product Nos. 2 and 4: The tubing was propelled off the platform. Product No. 3: The tubing exploded.

A testing of some of the above products for calorific value gave the following results:

Average B.t.u. per lb.

Product Nos. '2 and 3 5,780

Product No. 4 5,760

The aforesaid B.t.u. values coincide with the combined calorific values of the free carbon and the carbon and hydrogen contents of the gelled hydrocarbon plasticizer.

In the foregoing disclosure it will be seen that we have produced a propellant fuel comprising solid reactive material consistingof one or a combination of strong oxidizing agents incorporated with a form of finely-divided carbon and gelled hydrocarbon plasticizer, to give a moldable material insofar as preferred embodiments are considered. It may be found, however, that in some instances it is desirable to have a powdery material. The virtues of a propellant of. this semi-solid type, over rigidly solid' fuel, include complete stability over a wide range oftemperature and pressure conditions, as well as complete resistance to impact forces.

In addition to optimum safety in handling, the propellant may, under normal atmospheric conditions, be stored indefinitely without deterioration or spontaneous combustion. This is a definite advantage over rigid solid fuels containing the same powerful oxidizing agents, reference being made to the book entitled Rocket Propellants, by F. A. Warren, Reinhold Publishing Co., New York, N.Y., 1958, and particularly the propellant identified as JPN on p. 9 thereof. It appears, aside from the favorable properties mentioned above, that this semi-solid type of fuel has steadier burning rate than other fuels of similar type, since stratification of the constituents, inclusion of air pockets, and segregations are eliminated.

Aluminum naphthenate with a high percentage range of aluminum, as above mentioned, may be prepared in t accordance with the copending Biggart patent application, Serial No. 749,298, filed July 17, 1958, where the formulation procedure is set forth as follows: A concentrated solution of caustic is slowly stirred into the naphthenic acid. The ensuing reaction causes the mixture to become very hot, and by the time all of the caustic solution has been added, the entire mass becomes a solid gel. It is important to note that the full amount of liquid in the reaction mix must become a solid lump within a few minutes of adding the full quantity of caustic solution. If this does not take place, the ultimate result will be a batch of ordinary aluminum naphthenate assaying a lower metal content than 7%.

The solid lump of sodium naphthenate is then dissolved in about seven times as much cold water and heated until complete solution is attained, the solution being clear and bright. Thereafter approximately an equal amount of an equally dilute aluminum sulfate solution is poured slowly into the naphthenate with constant stirring. A cream-colored, almost white, precipitate of aluminum naphthenate forms at once. .The precipitate is permitted to settle for a few minutes and the clear aqueous solution drawn off. It is thereafter washed several times with fresh water and finally filtered. The product, which may be dried in a current of warm air or by any other suitable means, is a finely divided powder assaying over 7% aluminum.

The chief property of the aluminum naphthenate so produced is its ability to immediately form a clear, transparent gel in cold organic solvents by simple stirring. Small quantities of the aluminum naphthenate will sharply increase the viscosity of paints or varnishes giving them an attractive body. The aluminum naphthenate can similarly thicken lubricants and greases. To gel gasoline, it has an advantage over aluminum stearate in that the aluminum naphthenate gel remains unaffected by heat. In one particular test, some thin automotive lubricating oil had added thereto 2% of the aluminum naphthenate. There resulted a high viscosity (or heavy) oil. A beaker full. of this heavy oil was heated on a Bunsen burner for over half an hour, but despite the application of heat the viscosity of the new oil did not change in any way, the oil getting neither thicker nor thinner.

The following Specific example shall serve to illustrate the above practice.

A concentrated caustic soda solution was prepared by dissolving 200 grams of sodium hydroxide in 175 cc. of water, forming 250 cc. of concentrated caustic solution. To 50 grams of naphthenic acid in a cc. beaker 35 cc. (52.5 grams), of aforementioned caustic soda solution was added slowly with constant stirring. The reaction mixture became Very hot and was completely gelled by the time all of the caustic soda solution had been added. The solid lump weighing 102.5 grams was subsequently dissolved by adding it to 750 cc. of cold water (in a two-liter beaker) and gently heating until complete dissolution had been attained.

Thereafter 900 cc. of a 10% solution of Al (SO .18

H O was slowly added with constant stirring. A light cream-colored precipitate of aluminum naphthenate formed at once. The precipitate was permitted to settle, clear water solution decantered off and the precipitate washed twice with fresh water. The precipitate was then filtered and dried in a current of hot air. The yield was 56.1 grams. Its aluminum content was 7.55%.

Inasmuch as formation of an actual gel of sodium naphthenate is important, the caustic solution concentration must be within a relatively narrow range of 50-55% NaOH. Also from about 65-75 cc. of such NaOH solution must be employed per hundred grams of naphthenic acid. Similarly the concentration of the aluminum sulfate in the precipitating solution should be within the range of about -15%, while the ultimate solution of sodium naphthenate should also be in about 515% concentration. The later is achieved by dissolving the gel in about 5-10 times its weight of cold water.

Having now described the invention in detail in accordance with the requirements of the patent statutes, those skilled in this art will have no difficulty in making changes and modifications in the individual parts or their relative assembly in order to meet specific requirements or conditions. Such changes and modifications may be made without departing from the scope and spirit of the invention, as set forth. in the following claims.

Having thus described our invention, what We claim as new and desire to secure by Letters Patent is:

1. A semi-solid fuel which may be stored indefinitely without deterioration, smooth burning with propelling force so as to be suitable for rocket propulsion consisting essentially of between 20%. and 35% of a liquid hydrocarbon gelled by means of aluminum naphthenate containing about 7% of aluminum chemically combined in the aluminum naphthenate and between 80% and 65% of a mixture of between 5% and 10% of finely-divided carbon and between 95% and 90% of an oxidizing material selected from the group consisting of ammonium nitrate, "ammonium perchlorate and magnesium perchlorate.

2. A semi-solid fuel which may be stored indefinitely without deterioration, smooth. burning with propelling force so as to be suitable for rocket propulsion consisting essentially of between and 35% of a liquid in the aluminum naphthenate sufiicient to gell said by.-

drocarbon, the remainder being an oxidizing mixture" consisting of about 5% of lamp black and about 95% 6. A fuel which may be stored indefinitely without deterioration, smooth burning with propelling force so as to be suitable for rocket propulsion consisting essentially of between 20% and 35% of a liquid hydrocarbon gelled by aluminum naphthenate containing about 7% of aluminum chemically combined in the aluminum naphthenate and between 80% and 65% of a mixture consisting of between 5% and 10% of an oxidizable material selected from the group consisting of finely-divided carbon and metal powders, and between 95 and 90% of an oxidizer selected from the group consisting of ammonium nitrate, ammonium perchlorate and magnesium perchlorate.

7. A semi-solid fuel which may be stored indefinitely without deterioration, smooth. burning with propelling force so as to be suitable for rocket propulsion compris-'. 7 ing approximately of a plasticizing agent produced by adding approximately 7.3% of aluminum naphthenate containing approximately 7% of aluminum chemically combined in the aluminum naphthenate to a liquid bydrocarbon, and approximately 75% of an oxidizing mixture consisting of approximately 5% lamp black and approximately 95% ammonium perchlorate.

8. A semi-solid fuel which may be stored indefinitely without deterioration, smooth burning with propelling force so as to be suitable for rocket propulsion, consisting essentially. of between 20% and of a liquid hydrocarbon'gelled by means of from 2.6'to 13.6% of sisting of the nitrates, chlorates, perchlorates, peroxides containing about 7 of aluminum chemically combined of a mixture of ammonium nitrate and ammonium perchlorate.

4. A semi-solid fuel which may be stored indefinitely without deterioration, smooth burning with propelling force so as to be suitable for rocket propulsion comprising about 25% of a plasticizing agent produced by adding about 7.3% of aluminum naphthenate containing about 7% of aluminum chemically combined in the aluminum naphthenate to a liquid hydrocarbon, and

naphthenate to a liquid hydrocarbon, and about of an oxidizing mixture consisting of about 5% lamp black, about 47.5% ammonium nitrate, and about 47.5 ammonium perchlorate.

and picrates of ammonia, alkali and alkaline earth metals, *nitrocellulose and nitroglycerine.

9. A semi-solid fuel suitable for rocket propulsion I consisting essentially of between 20% and 35% of a liquid hydrocarbon gelled by means of aluminum naphthenate containing about 7% of aluminum chemically combined in the aluminum naphthenate and between and 65 of a mixture of oxidizable and oxidizing materials,

said mixture being between 5% and 10% of oxidizable material selected from the group consisting of lamp black, finely-divided calcined petroleum coke, ground charcoal and coal, and between 95% and of oxidizing ma- 1 terial selected from the group consisting of the nitrates, chlorates, perchlorates, peroxides and picratesof am-- ,monia, alkali and alkaline earth metals, nitrocellulose and nitroglycerine.

References Cited in the file of this patent UNITED STATES PATENT.)

Jet Propulsion, Air Technical Service Command (1946 page 152. 

9. A SEMI-SOLID FUEL SUITABLE FOR ROCKET PROPULSION CONSISTING ESSENTIALLY OF BETWEEN 20% AND 35% OF A LIQUID HYDROCARBON GELLED BY MEANS OF ALUMINUM NAPHTHENATE CONTAINING ABOUT 7% OF ALUMINUM CHEMICALLY COMBINED IN THE ALUMINUM NAPHTHENATE AND BETWEEN 80% AND 65% OF A MIXTURE OF OXIDIZABLE AND OXIDIZING MATERIALS, SAID MIXTURE BEING BETWEEN 5% AND 10% OF OXIDIZABLE MATERIAL SELECTED FROM THE GROUP CONSISTING OF LAMP BLACK, FINELY-DIVIDED CALCINED PETROLEUM COKE, GROUND CHARCOAL AND COAL, AND BETWEEN 95% AND 90% OF OXIDIZING MATERIAL SELECTED FROM THE GROUP CONSISTING OF THE NITRATES, CHLORATES, PERCHLORATES, PEROXIDES AND PICRATES OF AMMONIA, ALKALI AND ALKALINE EARTH METALS, NITROCELLULOSE AND NITROGLYCERINE. 